Virgin said drivers had also experienced braking problems at Manchester Piccadilly station and in other places.

And there have been two recent instances of Pendolinos going through red signals in Warwickshire - the first at Rugby on October 21 and the second at Nuneaton on October 25.

The improvement notice to Virgin from the HSE said: "The braking arrangements for your Class 390 trains are not suitable and sufficient in conditions of low adhesion to ensure, so far as is reasonably practicable, the safety of employees, other railway staff and passengers."

On Thursday, a Virgin spokeswoman said: "Following the two incidents where a train has made contact with the buffer stops at Liverpool Lime Street at a very low speed, Virgin confirms that it's carrying out a full investigation with Network Rail and (the manufacturer) Alstom.

"Virgin Trains will also participate in the independent inquiry being undertaken by the Railway Safety and Standards Board.

"As a precautionary measure while the investigations
take place and we understand fully the issues, we have rebriefed drivers on low-adhesion driving techniques (to counter the problem of leaves on the line) and have revised the stopping point for trains at stations.

"We have also temporarily reduced the speed of these trains to 110mph."